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Got it figured out and refilled during my lunch break, I appreciate it!

Sent from my DROID RAZR using Bimmer App

Glad to hear that you figured out how to add DEF. There are two fill ports, the upper port is for the passive tank, the lower port is for the active tank. Together they hold about 6 gallons.
You should verify why you've got the low DEF light in the first place. According to BMW, DEF should not be required between services. So a couple of questions:
Is the car still under warranty?
When was the last service? / Or how many miles are on the car since the last service?
A low DEF warning could be symptomatic of other mechanical problems - OR an improperly serviced car at the last service. Search these forums for discussions about DEF.